Since brass, nor stone, nor earth, nor boundless sea,But sad mortality o’ersways their power,How with this rage shall beauty hold a plea,Whose action is no stronger than a flower?O! how shall summer’s honey breath hold out,Against the wrackful siege of battering days,When rocks impregnable are not so stout,Nor gates of steel so strong but Time decays?O fearful meditation! where, alack,Shall Time’s best jewel from Time’s chest lie hid?Or what strong hand can hold his swift foot back?Or who his spoil of beauty can forbid? O! none, unless this miracle have might, That in black ink my love may still shine bright.

Since he was wont to muse on mortal things, it seems fit that Shakespeare’s supposed birthday (the true date, like so much else about him, is unknown) is also the day he died. Death — sad mortality — loomed large to him, and so it’s a marvel of poetic irony that 400 years since the day he died, the world still bears witness to his life. So much of his surviving verse bears out his belief that verse could survive death, his will that it would. The miracle of his work is that it worked. His hand, after all, was strong enough. On this day, he’s not 400 years dead; he’s immortal.